The present invention relates to novel derivatized polyalkylamine additives for fuels and lubricants, processes for the preparation of these additives and fuels and lubricants and additive concentrates which contain these novel additives.
Carburettors and intake systems of gasoline engines as well as injection system for fuel metering in gasoline and diesel engines are becoming contaminated with impurities to an increasing extent. The impurities are the result of dust particles from the air taken in by the engine, uncombusted hydrocarbon residues from the combustion chamber and the vent gases from the crank case which are passed into the carburettor.
These residues shift the air/fuel ratio during idling and in the lower part-load range so that the mixture becomes richer and the combustion more incomplete. As a result of this, the proportion of uncombusted or partially combusted hydrocarbons in the exhaust gas and the benzene consumption increase.
It is known that these disadvantages can be avoided by using fuel additives for keeping valves and carburettor or intake systems clean (cf. for example: M. Rossenbeck in Katalysatoren, Tenside, Mineralxc3x6ladditive, Ed. J. Falbe, U. Hasserodt, pp. 223, G. Thieme Verlag, Stuttgart 1978). Depending on the mode of action and preferred place of action of such detergent additives, a distinction is now made between two generations. The first generation of additives was only able to prevent the formation of deposits in the intake system, not to remove existing deposits. On the other hand, additives of the second generation can prevent and eliminate deposits (keep-clean and clean-up effect). This is permitted in particular by their excellent heat stability in zones of relatively high temperature, in particular in the intake valves.
The molecular structural principle of these additives of the second generation which act as detergents is based on the linkage of polar structures to generally relatively high molecular weight, nonpolar or oleophilic radicals. Typical members of the second generation of additives are products based on polyisobutene in the nonpolar moiety, in particular additives of the polyisobutylamine type.
Such detergents can be prepared by two different multistage synthesis processes, starting from polyisobutenes.
The first process involves chlorination of the polymeric parent structure, followed by nucleophilic substitution of the polymeric parent structure by amines or, preferably, ammonia. The disadvantage of this process is the use of chlorine, which results in the occurrence of chlorine- or chloride-containing products, which is not at all desirable today.
In the second process, the polyisobutylamines are prepared starting from polyisobutene, by hydroformylation and subsequent reductive amination according to EP 0 244 616.
If ammonia is used in the reductive amination in the second process, the reaction products of the ammonia usually display excellent efficiency with regard to keeping valves and carburettors clean, but they are at best neutral in their action on an engine lubricant, in particular with regard to their oil sludge-dispersing actions.
Additives which are particularly advantageous from the technical and economic point of view are therefore those which simultaneously combine the properties of detergents and dispersants and are obtainable by simple, chlorine-free synthesis processes.
Such additives are disclosed in EP 0 568 873. The latter describes xcex2-aminonitriles of the formula 
where
Ra is an aliphatic hydrocarbon radical having alkyl side groups and an average molecular weight of from 250 to 5,000 and Rb, Rc and Rd, independently of one another, are each hydrogen or C1-C8-alkyl or Rb and Rd are each phenyl,
and the corresponding N-alkyl-1,3-propylenediamine obtained by hydrogenation.
There is, however, an additional demand for further chlorine-free additive components in order to be able better to adapt the additives to the requirements of the respective application.
It is the object of the present invention to provide further compounds which are suitable as fuel and lubricant additives and are obtained by chlorine-free synthesis.
We have found that this object is achieved by providing derivatives of long-chain amines which are obtained by functionalization of the amine group by a cyanomethylation or by reaction with diketenes. For the purpose of the present invention, cyanomethylation is the linking of a cyanoalkyl group by its xcex1-carbon atom to an amine nitrogen.
The present invention relates in particular to compounds of the general formula I
Zxe2x80x94CH2xe2x80x94NY2xe2x88x92nHnxe2x80x83xe2x80x83(I)
where
n is 0 or 1,
Z is a straight-chain or branched polyalkyl radical having an average molecular weight of from about 150 to 40,000,
Y is a radical of the formula IIa or IIb 
xe2x80x83where
R, R1 and R2 are identical or different and, independently of one another, are selected from the group consisting of hydrogen, unsubstituted and substituted alkyl, alkenyl and alkynyl radicals and unsubstituted and substituted cycloalkyl, aryl and arylalkyl radicals which may contain one or more heteroatoms; and
A is an alkyleneimine radical of the formula III 
xe2x80x83where
m is an integer from 0 to 10;
Alk is straight-chained or branched, unsubstituted or substituted alkylene;
R3 is hydrogen, alkyl, alkenyl, alkynyl, aryl or, if Y is a radical of formula IIA, a keto radical of the formula IVa 
xe2x80x83where
R has the above mentioned meanings;
or, if Y is a radical of formula IIb, a cyano radical of the formula IVb 
xe2x80x83where
R1 and R2 have the above-mentioned meanings; or, if
n is O, one of the radicals Y may be a polyoxyalkylene radical of the formula (V) 
xe2x80x83where
q is an integer from 1 to 30,
Alk is as defined above and
E is hydrogen or C1-C6-alkyl.
According to a first preferred embodiment the present invention relates to cyanomethylated compounds of the formula I, where Z and n have the above-mentioned meanings and Y is a radical of the formula IIc 
where
R1, R2, R3 and m have the above-mentioned meanings,
R4 and R5 are identical or different and have the meanings stated above for R1 and R2, and
p is an integer from 2 to 5.
More preferred cyanomethylated additives are compounds of the formula I, where
Z, m, n and p have the above-mentioned meanings,
R1 and R2, independently of one another, are selected from the group consisting of hydrogen and alkyl, in particular C1-C10-alkyl,
R3 is hydrogen, alkyl, in particular C1-C10-alkyl, or a cyano radical of the formula IVb, and
R4 and R5, independently of one another, are each hydrogen or C1-C6-alkyl.
Particularly preferred additives are those in which Z is a radical composed of isobutene units and having a number average molecular weight of about 800-1500, n is 0 or 1 and Y is a group of the formula
xe2x80x94CR1R2xe2x80x94CN
where R1 and R2 independently of one another, are each hydrogen or C1-C10-alkyl.
According to another preferred embodiment the present invention relates in particular to diketene derivatives of the general formula Ia 
where Z, R and n have the above-mentioned meanings.
The radicals R, independently of one another, are preferably each hydrogen, a straight-chain or branched, unsubstituted or substituted C1-C30-alkyl, C2-C30-alkenyl or C2-C30-alkynyl radical or an unsubstituted or substituted C3-C8-cycloalkyl, phenyl, naphthyl or phenyl-C1-C12-alkyl or naphthyl-C1-C12-alkyl radical, which may carry one or more heteroatoms.
Compounds of the formula Ia, where Z has a number average molecular weight of from about 800 to 1500, n is 0 or 1 and radicals R are identical and selected from hydrogen and C1-C30-alkyl are particularly preferred.
The polyalkyl radical Z in compounds of the general formula (I) is preferably obtained by homo- or copolymerization of straight-chain or branched C2-C30-alkenes, preferably C2-C6-alkenes, particularly preferably C2-C4-alkenes. Particularly preferred C2-C4-alkenes are 1-alkenes, such as propylene, 1-butene and isobutene. For example, Z may be derived from a copolymer of 1-butene and isobutene, and Z may likewise have an average molecular weight of from about 800 to about 1500.
Alkyl radicals which may be used according to the invention are straight or branched, saturated hydrocarbon chains of 1 to 30 carbon atoms. Examples are C1-C6-alkyl, such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, iso-butyl, tert-butyl, n-pentyl, sec-pentyl, iso-pentyl, n-hexyl or 1-, 2- or 3-methylpentyl, long-chain alkyl radicals, such as straight-chain heptyl, octyl, nonyl, decyl, undecyl, lauryl, tridecyl, myristyl, pentadecyl, palmityl, heptadecyl, stearyl, nonadecyl, arachinyl, behenyl, lignoceryl, ceryl and myricyl, and the singularly or multiply branched analogues thereof. Preferred long-chain radicals are lauryl, myristyl, palmityl, stearyl and arachinyl.
Alkenyl radicals which may be used according to the invention are straight or branched hydrocarbon chains having at least one carbon-carbon double bond and having 2 to 30 carbon atoms. Examples of mono unsaturated C2-C30-alkenyl radicals are C2-C6-alkenyl radicals such as vinyl, allyl, 1-propenyl, isopropenyl, 1-, 2- or 3-butenyl, methallyl, 1,1-dimethylallyl, 1-, 2-, 3-, 4- or 5-hexenyl, long-chain radicals, such as straight-chain heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, pentadecenyl, palmitoleyl, icosenyl and triacontenyl, and the branched analogues thereof, where the double bond may occur in any desired position. According to the invention, both the cis and the trans isomers of the above C2-C30-alkenyl radicals are included. A preferred mono unsaturated long-chain radical is oleyl.
Alkynyl radicals which may be used according to the invention are straight or branched hydrocarbon chains having at least one carbon-carbon triple bond and 2 to 30 carbon atoms. Examples include ethinyl, 1- or 2-propinyl, 1-, 2- or 3-butinyl and the corresponding alkynyl analogues of the above-mentioned alkenyl radicals.
Cycloalkyl radicals which may be used according to the invention include C3-C8-cycloalkyl radicals such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclopropylmethyl, cyclopropylethyl, cyclopropylpropyl, cyclobutylmethyl, cyclobutylethyl, cyclopentylethyl, cyclopentylpropyl and the like.
Examples of aryl radicals which may be used according to the invention are phenyl and naphthyl.
Arylalkyl radicals which may be used according to the invention are in particular phenyl-C1-C10-alkyl and naphthyl-C1-C10-alkyl, the C1-C10-alkyl moiety being as defined above.
The cycloalkyl, aryl and arylalkyl groups which may be used according to the invention may, if required, contain 1 or more, for example 1 to 4, heteroatoms, such as O, S and N, oxygen and nitrogen being preferred as heteroatoms. Examples of cyclic heteroalkyl radicals are tetrahydrofuranyl, piperidinyl, piperazinyl and morpholinyl. Examples of heteryl groups are 5- or 6-membered aromatic ring systems which comprise from 1 to 4 of the stated heteroatoms, eg. furyl, pyrrolyl, imidazolyl, pyrazolyl, oxazolyl, isoxazolyl, oxadiazolyl, tetrazolyl, pyridyl, pyrimidinyl, pyrazinyl, pyradizinyl, triazinyl, tetrazinyl and the like.
Straight-chain or branched alkylene radicals which may be used according to the invention include straight-chain C1-C10-alkylene radicals, eg. ethylene, propylene, butylene, pentylene and hexylene, and branched C1-C10-alkylene radicals, eg. 1,1-dimethylethylene, 1,3-dimethylpropylene, 1-methyl-3-ethyl-propylene, 2,3-dimethylbutylene, 1,3-dimethylbutylene, 1,1-dimethylbutylene, 1,2-dimethylpentylene and 1,3-dimethylhexylene.
Examples of substituents which are suitable according to the invention are C1-C6-alkyl, C1-C6-alkoxy, C2-C6-alkenyl, C1-C6-alkanoyl, such as acetyl and propionyl, nitro and amino.
The present invention furthermore relates to a process for the preparation of compounds of the general formula (I), wherein a polyalkylamine of the general formula VI 
where
Z has the above-mentioned meanings,
W is hydrogen or xe2x80x94Axe2x80x94H, and
A is an alkyleneimine radical of the formula VII 
xe2x80x83where Alk and m have the above-mentioned meanings and R6 is hydrogen, straight-chain or branched alkyl, alkenyl or alkynyl or aryl, either
a1) is reacted with at least one diketene of the formula IX 
xe2x80x83where R has the above mentioned meanings, in an inert solvent, in order to obtain a compound of formular I, where in at least one radical Y is of formula IIa, or
a2) is reacted with hydrocyanic acid or a salt thereof and least one compound of the general formula VIII 
xe2x80x83where R1 and R2 have the above-mentioned meanings in order to obtain a compound of formula I wherein at least one radical Y is of formula IIb.
The reaction a2) preferably is carried out in an aqueous medium in the presence of a phase-transfer catalyst.
If, in the reaction product obtained, according to a1) or a2) W is hydrogen, this can, if desired, be substituted in a conventional manner by a group of the formula V 
where Alk, E and q have the above-mentioned meanings.
The derivatization of the polyalkylamines with diketenes according to process a1) to give the novel diketene-derivatized compounds is carried out in a manner known per se by adding the diketene to the polyalkylamine in the absence of a solvent or in an inert solvent, while cooling, at room temperature or at elevated temperatures, depending on the reactivity of the reactants. Examples of suitable solvents include sulfur- and chlorine-free solvents, such as relatively high-boiling hydrocarbons, eg. n-hexane, n-octane, n-decane or isododecane, or dipolar aprotic solvents, such as anhydrous tetrahydrofuran. The polyalkylamine is preferably dissolved in a suitable solvent, and the diketene, if necessary dissolved in the same solvent, is added dropwise while stirring. The reaction products obtained can be used without further purification, if necessary after distilling off the solvent or removing excess reagents.
According to the prior art, the cyanomethylation of amine is usually carried out by the xe2x80x9cStrecker-Synthesisxe2x80x9d (cf. for example: Strecker, Ann. Chem. 75, (1850), 27; Kendall, McKenzie, Org. Synth., 9, (1929), 4; H. Bucherer, A. Grolee, Chem. Ber. 39, (1906), 992; E. Knoevenagel, Chem. Ber. 37, (1904), 402; DE 2 107 757; DE 2 624 891) by reacting the amine with aqueous formaldehyde and hydrocyanic acid. Reaction of polyisobuteneamines of the above formula VI with hydrocyanic acid or salts of hydrocyanic acid and formaldehyde or paraformaldehyde does not lead to the desired reaction, even with the addition of solubilizers. Surprisingly, however, it was found, according to the invention, that the novel cyanomethylated additives can be prepared according to process a2) in surprisingly good yield by adding a phase-transfer catalyst.
The nucleophilic substitution of halogenated hydrocarbon compounds with sodium cyanide under phase-transfer catalysis is generally known (C. M. Starks, J. A. Chem. Soc. 93, (1971), 195), as is the hydrocyanation of carbonyl compounds with the phase-transfer catalysts (C. L. Liotta, A. M. Dabdoub and L. H. Zalkow, Tetrahedron Lett., (1977), 1117). However, the use of phase-transfer catalysts in the cyanomethylation of hydrophobic amines is novel. It is surprising that the reaction is accelerated although formaldehyde is added in an aqueous solution.
Suitable phase-transfer catalysts for carrying out the novel process a2) include quaternary ammonium and phosphonium salts, although quaternary ammonium salts are preferred. Examples of phase-transfer catalysts which may be used are benzyltriethylammonium chloride, tetrabutylammonium bromide, methyltricaprylammonium chloride and methyltributylammonium chloride and the corresponding halogen-free forms of these compounds.
The novel preparation process a2) is preferably carried out by a procedure in which the polyalkylamine of the formula VI is dissolved in a suitable solvent, eg. tetrahydrofuran or another dipolar aprotic solvent, and the phase-transfer catalyst is added to the solution. An aqueous cyanide solution in which the ketone compound of the formula VIII has been dissolved is then added. The reaction mixture is heated to about 40-70xc2x0 C. and the pH of the solution is kept at about 8-9. After the end of the reaction, the organic phase is separated off and the desired additive is isolated therefrom.
If mixtures of ketone compounds of the general formula VIII are used in the novel preparation process, the novel additives simultaneously contain different terminal cyano groups of the formula IIb.
The polyalkylamines of the general formula VI can be prepared by hydroformylation of reactive polyalkenes and subsequent reductive amination of the oxo product. The reactive polyalkenes having an average molecular weight of from about 150 to 40,000 are homo- or copolymers of straight-chain or branched C2-C30-alkenes, preferably C2-C6-alkenes, in particular C2-C4-alkenes. Reactive polyalkenes include unsaturated polymers of high chemical homogeneity, more than 10% of the double bonds being in the alpha position. A possible method for the preparation of reactive polyalkenes is disclosed in DE 27 02 604. Particularly preferred reactive polyalkenes are those which are prepared from 1-alkenes, in particular propylene, 1-butene, isobutene or mixtures thereof.
Other suitable polyalkylamines of the general formula VI are amines according to EP 0 244 616 and EP 0 695 338, the content of which is hereby incorporated by reference. EP 0 244 616 describes in particular polyalklamines in which Z is derived from isobutene and up to 20% by weight of n-butene, it being possible for the molecular weight of the polyisobutene radical to be from about 300 to about 5000. EP 0 695 338 describes in particular polyalkylamines in which Z is derived from one or more 1-n-alkenes of 3 to 6 carbon atoms and up to 50-% by weight of ethene, it being possible for Z to have about 20-400 carbon atoms.
However, an important criteria for all polyalkylamines which may be used according to the invention is that they contain at least one primary or secondary amine group which can be derivatized by cyanomethylation or by reaction with diketenes, as described above.
Additives particularly preferred according to the invention are those which are prepared starting from polybutylamines and polyisobutylamines of the formula VI and which are disclosed in EP 0 244 614.
The present invention furthermore relates to lubricant compositions which contain at least one novel polyalkylamine derivative according to the above definition, if necessary in combination 40 with further conventional lubricant additives. Examples of conventional additives are corrosion inhibitors, antiwear additives, viscosity improvers, detergents, antioxidants, antifoams, lubricacy improvers and pour point improvers. The novel compounds are usually present in amounts of from about 1 to 15, preferably from about 0.5 to 10% by weight, based on the total weight of the composition.
Examples of lubricants prepared according to the invention include oils and greases for motor vehicles and industrially used drive assemblies, in particular engine oils, gear oils and turbine oils.
The present invention furthermore relates to fuel compositions, for example fuels for gasoline and diesel engines, which contain the novel additives. The novel compounds serve therein in particular as detergents for keeping the fuel intake system clean. Owing to their dispersing properties, they have an advantageous effect on the engine lubricant, which they can enter during operation.
To test the novel products with regard to their dispersant properties, it is possible to use a spot test, as described, for example by A. Schilling in xe2x80x9cLes Huiles pour Moteurs et la Graissage des Moteursxe2x80x9d, Vol. 1, 1962, page 89 et seq., in a somewhat modified form.
The novel polyalkylamine derivatives are metered into commercial fuels in a concentration of from about 20 to 5000, preferably from about 50 to 1000, mg/kg of fuel. The novel additives can, if required, also be added together with other known additives.
While novel additives in which Z has a number average molecular weight of about 2000-40,000 are preferably used in lubricant compositions, compounds in which Z has a number average molecular weight of about 150-5000, preferably about 500-2500, and in particular about 800-1500, are particularly useful for use as fuel additives.
Finally, the present invention relates to additive mixtures which, in concentrated form, contain at least one novel compound in combination with other fuel additives, in particular detergents and dispersants. A combination with, for example, polyisobutylamines disclosed in U.S. Pat. No. 4,832,702 is particularly preferred.
In principle, any known product from among the products suitable for this purpose, may be used as a detergent component in the novel additive mixtures, said products being described, for example, in J. Falbe, U. Hasserodt, Katalysatoren, Tenside und Mineralxc3x6ladditive, G. Thieme Verlag, Stuttgart, 1978, page 221 et seq., or in K. Owen, Gasoline and Diesel Fuel Additives, John Wiley and Sons 1989, page 23 et seq.
N-containing detergents, for example compounds which contain an amino or amido group, are preferably used. Polyisobutylamines according to EP 0 244 616, ethylenediaminetetraacetamides and/or ethylenediaminetetraacetimides according to EP 0 188 786 or polyetheramines according to EP 0 356 725 are particularly suitable, and reference may be made to the definitions in these publications. Owing to their method of preparation, the products described there likewise have the advantage of being chlorine- or chloride-free.
On the other hand, these additives may also be combined with carrier oils. In particular, carrier oils based on polyalkylene glycol, for example corresponding ethers and/or esters, as described in U.S. Pat. No. 5,004,478 or DE 38 38 918 A1, are suitable. Polyoxalkylenemonooles having terminal hydrocarbon groups (U.S. Pat. No. 4,877,416) or carrier oils as disclosed in DE 41 42 241 may also be used.